Breaking pin device as stand alone relief system

[EGT01]

Just recently, I've had to evaluate an existing relief system which used a rupture pin device as a single component relief system. I've seen in ASME Sec VIII, Div 1, UG-127b which states "Breaking pin devices shall not be used as single devices but only in combination between the safety or safety relief valve and the vessel."

Based on info provided by the rupture pin valve manufacturer, a rupture pin valve (aka buckling pin valve) certainly is not a breaking pin since it does not fail by shear or tension (buckling pins bend). The manufacturer referenced an ASME code case 2091, which to summarize, allows a rupture pin valve as a single component relief system.

As a question more out of curiosity than necessity, does anyone know what the concerns would be for using a breaking pin device as a stand alone relief system?

I did a quick search on the web and really couldn't find much on breaking pin devices. I see Crosby offers a combination breaking pin/spring loaded relief valve (model JQ) for chlorine rail cars.

 

[CHD01]

EGT01:

The following web site might help. As I understand it, the advantage of the pin is that you can operate close to buckling pressure without leakage; the disadvantage is that its a non-reclosing application like a rupture disk. We have not used any at our site; and it does not seem to get a lot of support in the corporation.

http://www.rupturepin.com/application.htm

Good Luck! The more you learn, the less you are certain of.

 

[TD2K]

I know of an installation on the North Slope in Alaska where a buckling pin device was used to replace a rupture disk. The rupture disk was on a flare header and was used to bring the emergency ground flare into service on high header pressure.

As I was told (I didn't work on the facility but worked later with one of the engineers who was involved with this project), the rupture disk was subject to premature opening due to the cyclic nature it saw AND was a royal PITA to replace, especially during the winter. The buckling pin device on the other hand was easy to reset, is not suspectible to fatigue failure (per the manufacturer when I talked to them about these) and can operate much closer to set pressures than a rupture disk.

As CHD01 points out, it's a non-reclosing device which would rule it out for a lot of applications.

 

[CHD01]

Yes - I've always felt these pins had a place in the market for difficult rupture disk installations; just haven't found the occassion to use yet.
The more you learn, the less you are certain of.

 

[EGT01]

Thanks for the replies. This is the first rupture pin I've come across and before I had much chance to evaluate the application I was pulled off to work on something else.

About as far as I got was to know the Corporate guidelines basically quoted the section in ASME saying breaking pin devices shall not be used as single devices but gave no explanation for this. So I was questioning if it was proper to install as such. I heard from the engineer that continued with the evaluation saying it was information such as found on the web site CHD01 noted that was basis for installing it stand-alone.

Can't think of any reason why this type device would be any different from a rupture disk for it to be not recommended stand-alone.

 

[svanels]

Shear pin relieve valves are commonly used on mudpumps (positive displacement pumps) in the drilling industry. The mud is used to remove the cuttings from the hole.

The pin in this cases is just a plain nail, and the limiting pressure determines the size (diameter). It is strictly forbidden to substitute it by an allen key (machine steel) or the preferred welding rod.
Steven van Els
SAvanEls@cq-link.sr